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Type: Artigo de periódico
Title: Magnetic phase evolution in the LaMn(1-x)FexO(3+y) system
Author: de Lima, OF
Coaquira, JAH
de Almeida, RL
de Carvalho, LB
Malik, SK
Abstract: We have investigated the crystal structure and magnetic properties for polycrystalline samples of LaMn1-xFexO3+y, in the whole range 0.0 <= x <= 1.0, prepared by solid state reaction in air. All samples show the ORT-2 orthorhombic structure that suppresses the Jahn-Teller distortion, thus favoring a ferromagnetic (FM) superexchange interaction between Mn3+-O-Mn3+. For x = 0.0 the oxygen excess (y approximate to 0.09) produces vacancies in the La and Mn sites and generates a fraction around 18% of Mn4+ ions and 82% of the usual Mn3+ ions, with possible double-exchange interaction between them. The Fe doping in this system is known to produce only stable Fe3+ ions. We find an evolution from a fairly strong FM phase with a Curie temperature T-C similar to 160 K, for x = 0.0, to an antiferromagnetic (AFM) phase with T-N = 790 K, for x = 1.0, accompanied by clear signatures of a cluster-glass behavior. For intermediate Fe contents a mixed-phase state occurs, with a gradual decrease (increase) in the FM (AFM) phase, accompanied by a systematic transition broadening for 0.2 < x < 0.7. A model based on the expected exchange interaction among the various magnetic-ion types accounts very well for the saturation magnetization (M-S) dependence on Fe doping. (C) 2009 American Institute of Physics. [DOI: 10.1063/1.3054323]
Country: EUA
Editor: Amer Inst Physics
Rights: aberto
Identifier DOI: 10.1063/1.3054323
Date Issue: 2009
Appears in Collections:Unicamp - Artigos e Outros Documentos

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